Phylum Annelida are ubiquitous metazoans found in almost every terrestrial and aquatic habitat on Earth. Historically, taxonomic studies on the phylum have been focused largely on its majorgroups, polychaetes, oligochaetes and leeches, so that while family-level keys for each group are available, no single-source identification guide exists to the world’s annelid families. Here, the first illustrated linear key to annelid families is provided and family-level descriptions and diagnoses that distinguish individuals of each family from those of other families in the phylum are updated. This information is generated from an annelid DELTA database of 334 characters and 166 mostly family-level taxa. A link is provided to downloadable software (ANNiKEY Interactive) allowing the same data to be interrogated using the open-source DELTA program Intkey, which enables both interactive identification and taxonomic query functionality. For each family-level taxon, a diagnosis, full description, links to taxonomic data at the World Register of Marine Species, illustrations of diagnostic features, and a summary of the recent literature, including a list of published keys to genera and species are provided.

A new species, Vitronuracheni sp. nov. (Collembola: Neanuridae) is described from Yongzhou, Hunan Province, China. The new species is characterized by the combination of following characters: 2+2 uncolored big eyes; labral chaetotaxy as 0/2, 2; cephalic tubercle Fr with chaeta O; cephalic tubercles Dl, L and So fused; mandibles with four teeth; maxillae with two lamellae, the long one with a tiny tooth and the short one with pointed tip; labrum truncated; claw without inner tooth; and femur and tibiotarsus with a tenant chaeta. Yuukianuraszeptyckii Deharveng & Weiner, 1984 was reported from China for the first time. Observations of a cultured population of Y.szeptyckii revealed feeding preferences and behavior that differ from those previously reported in other members of Neanurinae. A checklist of Yuukianura species and distributions is also provided.

Four new species of the jumping spider genus Synagelides Strand, 1906 are described from China: S.dajueshan K. K. Liu, sp. nov. (♂, ♀; Jiangxi Province), S.guangfeng K. K. Liu, sp. nov. (♂, ♀; Jiangxi Province), S.kangding K. K. Liu, sp. nov. (♂, ♀; Sichuan Province), and S.wuyuan K. K. Liu, sp. nov. (♂, ♀; Jiangxi Province). Furthermore, S.himalaicus Bohdanowicz, 1987, stat. res. (♂, ♀; Tibet Autonomous Region) is reinstated as a valid species and recorded from China for the first time, with S.jiricus Bohdanowicz, 1987, syn. nov. designated as its junior synonym. All species are comprehensively illustrated with diagnostic photographs and SEM images, and a distribution map is also provided. The geographic distribution of this genus in China and their adaptations are discussed.

This study reviews the Chinese representatives of Amaurobius, and a new genus, Sinoamaurobius Kong, Zhang & Wang, gen. nov., is described to accommodate seven species, including three new species and four species transferred from Amaurobius: Sinoamaurobiusguangwushanensis (Wang, Irfan, Zhou & Zhang, 2023), comb. nov., S.songi (Zhang, Wang & Zhang, 2018), comb. nov., S.spinatus (Zhang, Wang & Zhang, 2018), comb. nov., S.wulongdongensis (Wang, Irfan, Zhou & Zhang, 2023), comb. nov., S.baima Kong, Zhang & Wang, sp. nov. (♀, Sichuan), S.chengkou Kong, Zhang & Wang, sp. nov. (♂♀, Chongqing) and S.yintiaoling Kong, Zhang & Wang, sp. nov. (♂♀, Chongqing). Additionally, we also describe three new Amaurobius species: A.foping Kong, Zhang & Wang, sp. nov. (♀, Shaanxi), A.pingwu Kong, Zhang & Wang, sp. nov. (♂♀, Sichuan) and A.yushen Kong, Zhang & Wang, sp. nov. (♂♀, Chongqing and Hubei). For all new species, morphological descriptions and photos of habitus and copulatory organs are provided.

Anemonefishes (Teleostei, Pomacentridae) comprise approximately 28 species of damselfishes that exclusively live symbiotically with sea anemones. Distribution ranges vary, with some species only found in few isolated islands and others with ranges that span almost the entire Indo-Pacific. The orange-fin anemonefish, Amphiprionchrysopterus shows a wide distribution, from Australia to French Polynesia, extending north to Micronesia and the Marshall Islands. Two main color morphs exist, with a morph that displays a white tail and a second morph that has an orange tail. In French Polynesia, only the orange-tail morph is present, while in the rest of the range, the white-tail morph is prevalent, while the orange-tail morph is also present, but very uncommon. Here we assessed the potential presence of a cryptic species in French Polynesia based on morphology, mitochondrial markers, and full genome sequencing. Morphological and genetic results were consistent in identifying a separate group in French Polynesia, which we describe here as a new species: the Polynesian anemonefish, Amphiprionmaohiensis.

In this paper the results of a Phoridae collection from Košice Zoo in eastern Slovakia are reported. An unusual trap method was employed – BG-Sentinel 2 mosquito traps combined with CO2 as an attractant. Between July and October 2023, 73 species of the Phoridae family were recorded, 24 of which are new to the Slovak fauna (1 species from the genus Woodiphora and 23 species from the genus Megaselia). As a result, the total number of Phoridae species documented in Slovakia has increased to 254.

Four new species of the poorly known genus Megapleonum Huang, Shih & Ahyong, 2018, are described from Guangdong Province, China: Megapleonum falxsp. nov. from Huizhou City, M. yangdongensesp. nov. from Yangjiang City, and both M. ferrumequinumsp. nov. and M. wangjianisp. nov. from Maoming City. These four new species are all morphologically and genetically distinct from each other and the two known congeners Megapleonum ehuangzhang Huang, Shih & Ahyong, 2018 and Megapleonum shenzhen Huang & Mao, 2021. The extremely divergent morphology of the gonopod 1 of these species alone immediately sets them apart, but there are also distinct differences in other characters, including the carapace, ambulatory leg, and maxilliped 3 exopod flagellum. A phylogeny constructed using the mitochondrial 16S rDNA reveals that all species of Megapleonum form a deep-rooted monophyletic group with significant interspecific genetic distances, supporting the generic placement and specific treatments of these new taxa. A key to the species of Megapleonum is also provided.

Afropisasanctaehelenae (Chace, 1966) was originally described from three specimens collected from Saint Helena Island, South Atlantic, and assigned to Pisa Leach, 1814. It is a poorly known species, and until now, no new records have been reported. Recently, this species was transferred to a new genus, Afropisa Muñoz, García-Raso, González, Lopes, dos Santos & Cuesta, 2023, based exclusively on morphology. Nearly 60 years on from the original description, another eight specimens of A.sanctaehelenae have been made available for further study and sequencing. Mitochondrial 16S rRNA and cytochrome c oxidase subunit I sequences confirm the assignment of this Chace species to Afropisa. Photographs of the male holotype and female paratype confirmed the presence of additional characters; consequently, the present work provides a redescription of this species.

This study documents the diversity and distribution of the subfamily Attageninae (Coleoptera: Dermestidae) in Saudi Arabia based on the examination of specimens from institutional and private collections, and field surveys using different trapping and collection methods. It enumerates 20 species belonging to two genera, Attagenus (19 species) and Telopes (one species). Six species are newly recorded for the country: Attagenusbarbieri Pic, 1946; A.jakli Háva, 2021; A.kadleci Háva, 2012; A.vanharteni Háva, 2009; A.yemensis Háva & Herrmann, 2014; and Telopestessellatus Reitter, 1887. Morphological examinations led to the exclusion of five previously misidentified species from the Saudi fauna: A.dichrous Roth, 1851; A.fasciolatus (Solsky, 1876); A.heydeni (Reitter, 1881); Telopesobtusus (Gyllenhal in Schönherr, 1808); and Telopesreitteri (Mroczkowski, 1968). The distribution of Attageninae reveals the influence of environmental gradients on species richness, with mid-altitude areas (601-1500 m) serving as biodiversity hotspots, hosting 14 species. Lowland and highland specialists display niche adaptation, with species like A.apicalis and A.logunovi restricted to low altitudes (≤ 600 m) and A.kadleci found exclusively in high-altitude environments (> 2000 m). Approximately 40% of the Attageninae species in Saudi Arabia are found within protected areas. This study identifies five endemic species in the Arabian Peninsula, including one exclusive to Saudi Arabia (A.logunovi). These findings increase the number of known attagenine species by 43% in Saudi Arabia and 7% in the Arabian Peninsula, highlighting the need for systematic surveys and taxonomic revisions to reveal the overlooked biodiversity in the region.

The genus Pseudobornella Baba, 1932 (Gastropoda, Nudibranchia, Dendronotidae), which was previously thought to be monotypic and restricted to the Western Pacific, is here expanded with the description of a second species, Pseudobornellaqingdaoensis sp. nov., discovered in the Yellow Sea, China. The new species is similar in general body shape to its sole congener, P.orientalis Baba, 1932, but these species can be distinguished based on both external morphology and internal anatomy. Phylogenetic analyses reconstructed by Bayesian inference and maximum-likelihood methods using concatenated mitochondrial (COI, 16S rRNA) and nuclear (H3) genes and species delimitation analyses support the monophyly of Pseudobornella as well as the separation of the two known species.